Retrograde intrarenal surgery for the treatment of renal stones in children: factors influencing stone clearance and complications

Safety and feasability of ureteroscopy for pediatric stone, in children under 5 Years (SFUPA 5): A French multicentric study

INTRODUCTION

Ureteroscopy (URS) can be proposed as first-line therapy for the management of pelvic stones from 10 to 20 mm and for lower ureteric stones in children. However, little is known about the success and the morbidity of URS in young children. Ureteroscopic treatment may present matters in young children because of the small size of the pediatric kidney and the small size of the collecting system.

OBJECTIVE

To assess safety and efficacy of URS for the treatment of urinary stones in children aged of 5 years or less.

STUDY DESIGN

After the institutional ethical board approval was obtained, we conducted a retrospective, analytic, multicentric study that included all URS performed between January 2016 and April 2022 in children aged of 5 years or less. In this non-comparative case series, anonymized pooled data were collected from 7 tertiary care centers of pediatric patients. Endpoints were the one-session SFR at 3 months and per and postoperatives complications. Descriptive statistics were applied to describe the cohort.

RESULTS

Eighty-three patients were included. For them, 96 procedures were performed at the median age of 3.5 years (IQR: 0.8-5) and median weight of 14 Kg (6.3-23). Median stone size was 13 mm (4-45). There were 65 (67 %) renal stones treated with flexible URS, most of which were in the renal pelvis (30 %) and in the lower calix (33 %). A ureteral access sheath was used in 91 % procedures. Preoperative ureteral stent was placed in 52 (54 %) of patients. None of patients had ureteral dilatation. The single-session SFR was 67.4 % (56.3 and 89.2 % for flexible URS and semi-rigid URS respectively) and children require 1.4 procedures to achieve complete stone clearance. The overall complication rate was 18.7 %, most of them were minor (Clavien I-II). Intraoperative perirenal extravasation (Clavien IIIb) due to forniceal rupture was documented in 6.2 % of cases, related to an increased intrapelvic pressure (IPP) performed in a closed pelvicalyceal system.

DISCUSSION

Pediatric urologists should be aware of forniceal rupture based on the presence of extravasation of contrast during endourological procedures especially when they have difficulties to reach lower caliceal stone in small patient.

CONCLUSION

URS in patients aged of 5 years or less, is a complex minimally invasive procedure with reasonable efficacy and low morbidity. Intrarenal stones treated by RIRS in young children carries the risk of additional procedures to complete stone clearance.

Comparison and Evaluation of Outcomes of Ureteroscopy and Stone Laser Fragmentation in Extremes of Age Groups (≤10 Years and ≥80 Years of Age): A Retrospective Comparative Analysis of over 15 Years from 2 Tertiary European Centres

AIM

To assess and compare the outcomes associated with ureteroscopy and laser fragmentation (URSL) for extremes of age group (≤10 and ≥80 years).

METHODS

Retrospective consecutive data were collected from two European centres for all paediatric patients ≤10 undergoing URSL over a 15-year period (group 1). It was compared to consecutive data for all patients ≥80 years (group 2). Data were collected for patient demographics, stone characteristics, operative details, and clinical outcomes.

RESULTS

A total of 168 patients had 201 URSL procedures during this time (74 and 94 patients in groups 1 and 2 respectively). The mean age and stone sizes were 6.1 years and 85 years, and 9.7 mm and 13 mm for groups 1 and 2 respectively. While the SFR was slightly higher in group 2 (92.5% versus 87.8%, p = 0.301), post-operative stent rate was also significantly higher in the geriatric population (75.9% versus 41.2%, p = 0.0001). There was also no significant difference in pre-operative stenting (p = 0.886), ureteric access sheath use (UAS) (p = 0.220) and post-operative complications. Group 1 had an intervention rate of 1.3/patient as compared to 1.1/patient in group 2. The overall complications were 7.2% and 15.3% in groups 1 and 2 respectively (0.069), with 1 Clavien IV complication related to post-operative sepsis and brief ICU admission in group 2.

CONCLUSION

The paediatric population had a marginally higher incidence of repeat procedure, but the overall SFR and complications were similar, and post-operative stent insertion rates were much better compared to geriatric patients. URSL is a safe procedure in the extremes of age groups with no difference in the overall outcomes between the two groups.

Comparison of single-use flexible ureteroscopes with a reusable ureteroscope for the management of paediatric urolithiasis

INTRODUCTION

To compare the efficacy, side effects, and cost-effectiveness between a single-use digital flexible ureteroscope and a reusable flexible ureteroscope in the treatment of paediatric renal stones.

METHODS

This analytic, case-control, monocentric study included all patients undergoing flexible ureterosopies for stone treatment. Between April 2016 and February 2019, a reusable (Flex-X^C®, Karl Storz) flexible ureteroscope was used (control group), whereas a single-use (Uscope®, PUSEN Medical©) flexible ureteroscope was used in all procedures from March 2019 to April 2021. Clinical and procedural outcomes, operative times, complication rates, hospital stay, and costs per procedure were evaluated.

RESULTS

Forty-three cases using a reusable flexible ureteroscope and thirty-nine using a single-use flexible ureteroscope were included in the study. Demographic patient characteristics, stone burden, location and composition, preoperative presence of a double-J stent, procedural outcomes, mean length of postoperative hospital stay, and complications (4.6% versus 5%, p = 0.81) were comparable between the two groups. Median operative duration for stone removal was 93 min (20-170) with reusable versus 81 min (55-107) with the single-use scope (p = 0.18). Scope failure occurred four times with the reusable scope and in no case with the single-use. The total cost per procedure associated with the use of single-use scopes (798 Euros) was lower than a reusable scope (1483.23 Euros).

DISCUSSION

Single-use flexible ureteroscopes were created to bypass the problems incurred when reusable scopes were damaged and therefore not available for use in surgical procedures. Single-use flexible ureteroscopes are always immediately available and ready to be used, even in urgent cases, as they typically do not require maintenance or sterilization. Compared with their reusable counterparts, single-use flexible ureteroscopes have similar digital performance (270°), image quality and we found no difference in the success and complication rates. Cost analysis of a reusable flexible ureteroscope must consider the purchase price, maintenance and repair costs, and decontamination costs (including handling, detergent, bacterial culture, transportation, and storage costs). In contrast, only purchase price is included in cost analysis for single-use flexible ureteroscopes. Our study suggests that single-use flexible ureteroscopes may be associated with lower costs per procedure than their reusable counterparts.

CONCLUSION

Single-use flexible ureteroscopes are an interesting alternative to their reusable counterparts, particularly in terms of material resource management. Cost analyses conducted using a low volume of cases representative of a paediatric urology division favour the use of single-use ureteroscopes.

Role of Pediatric Ureteral Access Sheath and Outcomes Related to Flexible Ureteroscopy and Laser Stone Fragmentation: A Systematic Review of Literature

Context

Flexible ureteroscopy and laser lithotripsy (FURSL) represent a good treatment option for pediatric urolithiasis. Scarce evidence is available about the safety and efficacy of the concomitant use of a ureteral access sheath (UAS) in the setting of pediatric ureteroscopy (URS).

Objective

To acquire all the available evidence on UAS usage in pediatric FURSL, focusing on intra- and postoperative complications and stone-free rates (SFRs).

Evidence acquisition

We performed a systematic literature research using PubMed/MEDLINE, Embase, and Scopus databases. The inclusion criteria were cohorts of pediatric patients <18 yr old, submitted to URS for FURSL, reporting on more than ten cases of UAS placement. The primary outcomes were prestenting rates, operating time, ureteric stent placement rates after surgery, rates and grades of complications, ureteral injuries, and overall SFR. A total of 22 articles were selected.

Evidence synthesis

In total, 26 intraoperative and 130 postoperative complications following URS with UAS placement were reported (1.8% and 9.18% of the overall procedures, respectively). According to the Clavien-Dindo classification, 32 were classified as Clavien I, 29 as Clavien II, 43 as Clavien I or II, six as Clavien III, and one as Clavien IV. Twenty-one cases of ureteral injuries (1.59%) were noted in the whole cohort; most of them were ureteral perforation or extravasation, and were treated with a temporary indwelling ureteric stent. The overall SFR after a single URS procedure was 76.92%; after at least a second procedure, it was 84.9%.

Conclusions

FURSL is a safe and effective treatment option for pediatric urolithiasis. UAS use was associated with a low rate of ureteric injuries, mostly treated and resolved with a temporary indwelling ureteric stent.

Patient summary

We performed a systematic literature research on the utilization of a UAS during ureteroscopy for stone treatment in pediatric patients. We assessed the outcomes related to the rates of intra- and postoperative complications and the rates of efficacy of the procedure in the clearance of stones. The evidence shows a low rate and grade of complications associated with UAS placement and good stone-free outcomes. A ureteric injury may occur in 1.6% of cases, but it is usually managed and resolved with a temporary indwelling ureteric stent.

Can cystinuria decrease the effectiveness of RIRS with high-power ho:yag laser in children? Outcomes from a tertiary endourology referral center

Cystinuria, which is the cause of cystine urolithiasis, accounts for 2-6% of all urinary stones in children, has a low prevalence with a high recurrence rate, making this metabolic disorder a therapeutic challenge in pediatric population. The aim of this work is evaluate the efficacy and safety of retrograde intra-renal surgery (RIRS) in pediatric patients with cystinuria and kidney stones smaller than 2 cm. Prospective study of 64 stones treated in 22 retrograde intra-renal surgeries (RIRS) in cystinuric pediatric patients with renal or proximal ureteral stones less than 2 cm. Average age of 9.5 years. The following data were analyzed: demographics, stone characteristics and surgical data with intra- and postoperative complications. Location of the stones was 68.7% in the calyces, 20.3% in the renal pelvis, and 9.3% in the ureteropelvic junction; 41% of cases had multiple locations. The average cystinuria level before the procedure was 825 mg/dL. The anatomy of 73% of the interventions increased the difficulty of flexible ureteroscopy and decreased stone free rates, because distorted renal anatomy was present: sclerosis of the pelvis or infundibulum, abnormal calyceal dilations, or excluded calyces. Intraoperative complications occurred in 18.2% of the procedures. Reno-vesical ultrasound was performed in all patients in the first postoperative month, with an SFR of 59%. Cystinuric patients are a challenge for pediatric urologists, decreasing the effectiveness of RIRS. However, it could be better treatment than SWL and with fewer complications than PCNL in the pediatric population with this disease.

Flexible ureterorenoscopy (RIRS) vs. Mini- percutaneous nephrolithotomy (MINI-PCNL) for renal stones 20–30 mm a prospective randomized study

Background

To evaluate the safety and efficacy of mini percutaneous nephrolithotomy (mini PCNL) and retrograde intrarenal surgery (RIRS) in treatment of kidney stones 20–30 mm.

Methods

A prospective randomized study of 70 patients who presented to the urology department with calyceal or renal pelvic stone of 20–30 mm between September 2017 and September 2019. Patients were randomly divided into two groups, Group A (Mini PCNL) consists of 35 patients who were treated with mini PCNL and Group B (RIRS) consists of 35 patients who were Achieving success of the technique was considered when the patient is stone-free or has radiologically insignificant residual fragments < 4 mm.

Results

The demographic data in this study were comparable in both groups. The stone size was 20.43 ± 2.2 mm in group A & 20.5 ± 2.1 in group B, with no statistical significance. Meanwhile, the operative time in group A was 59.71 ± 19.44 min and in group B was 80.43 ± 14.79 min with statistical significance difference (p value < 0.001), while Fluoroscopy time had a mean of 8.11 ± 2.05 min in group A & 5.8 ± 1.98 min in group B with statistically significant diffrence (p value < 0.001). The stone free rate (SFR) was 88.6% in mini PCNL and 82.9% in RIRS with no statistically significant difference (p value: 0.5).

Conclusion

RIRS and mini PCNL can be an effective and alternative option for treatment of renal stones 2–3 cm. Both techniques have relatively similar SFR but RIRS showed more operative time, on contrary Mini-PCNL has more operative and postoperative complications. A multicenter studies with larger numbers of patients will be more effective to confirm these results.

Factors associated with the stone-free status after retrograde intrarenal surgery in children

INTRODUCTION

Paediatric urolithiasis has a recurrent nature because it is frequently associated with metabolic or anatomical disorders or infectious conditions. The rising incidence of the disease with its recurrent nature emphasises the need for minimally invasive therapeutic options. In this study, we aimed to evaluate efficacy and factors affecting the success of retrograde intrarenal surgery (RIRS) in children.

MATERIALS AND METHODS

Patients who underwent RIRS were evaluated retrospectively. Two different flexible ureteroscopes (F-URS) were used (7.5F F-URS and 7.95F with a 4.9F bullet-shaped tip). Irrespective of size, all residual fragments were considered as failure. Age, stone size, stone localisation, Hounsfield Unit (HU), stone-free rate (SFR) and complications were evaluated.

RESULTS

Forty-six patients (29 boys and 17 girls) with a median age of 70.5 months (6-214 months) were treated with RIRS between August 2014 and November 2019. The median operative time was 60 minutes (45-120 minutes). The median follow-up was 26 months (3-65 months). Fourteen patients had lower pole and 10 patients had multiple stones. Ureteral access sheath (UAS) was used in 16 (35%) patients. SFR was 61%. The median number of general anaesthesia was 2 (min 1, max 5). Auxiliary semirigid URS, PCNL and repeat RIRS were required in 4, 6 and 5 patients, respectively. Two patients had postoperative febrile urinary tract infection (UTI) as a complication. Age was associated with post-operative febrile UTI. Presence of stones with HU lower than 700, being operated 4.9F F-URS and without UAS were associated with better SFR.

CONCLUSIONS

RIRS is a minimally invasive method with low complication rates in the treatment of childhood stone disease. Higher stone-free rates are obtained in low HU stones and cases in which we used 4.9 F tip F-URS.

Is Retrograde Intrarenal Surgery as Safe for Children as It Is for Adults?

INTRODUCTION

The primary aim of this study is to compare the efficacy and safety of retrograde intrarenal surgery (RIRS) among the children and adults with similar stone burdens and locations. Also, the secondary aim of this study is to identify the factors affecting the stone-free rates (SFRs) of RIRS.

METHODS

We retrospectively compared perioperative results, SFRs, and complication rates (CRs) between pediatric (group 1, n: 55) and adult (group 2, n: 220) age groups diagnosed with kidney stones and treated by flexible ureterorenoscopy using the same instruments. Furthermore, multivariate analysis was performed to determine the factors affecting the SFR.

RESULTS

A total of 275 patients (pediatric group: 55; adult group: 220) were included in this study. The mean age of pediatric and adult groups was 7.2 ± 5.3 and 43.9 ± 15.1, respectively. The mean stone size was 13.9 ± 6.6 mm in the pediatric group compared to 14.8 ± 6.7 mm in the adult group (p = 0.35). Stone localizations and number were similar. JJ stenting for passive dilatation and use of UAS were higher in the pediatric group (p = 0.002; p = 0.017). However, postoperative double pigtail stenting rate was higher in the adult group (p < 0.001). Total CR was 13.8% and mostly Clavien I-II, and no difference was observed between the 2 groups (p = 0.541). The SFRs between the groups were similar (pediatric group: 81.8%; adult group: 78.2%; p = 0.554). On multivariate analysis, stone size (p < 0.001) and lower calyx stone (p < 0.001) were the negative predictive factors for SFR.

CONCLUSION

There are small technical differences between pediatric patients and adult patients in our study, but RIRS in children is as safe and efficient as it is in adults.

Comparison of extracorporeal shockwave lithotripsy and retrograde intrarenal surgery in the treatment of renal pelvic and proximal ureteral stones ≤2 cm in children

Introduction:

We aimed to compare extracorporeal shockwave lithotripsy (ESWL) and retrograde intrarenal surgery (RIRS) in pediatric patients with ≤2 cm renal pelvis and proximal ureteral stones.

Methods:

Medical records of 165 pediatric patients who underwent shockwave lithotripsy (SWL) or RIRS for upper urinary system stones up to 2 cm between January 2014 and December 2018 were retrospectively reviewed. After exclusions, the remaining 130 patients included 73 in the SWL group and 57 in the RIRS group. The groups were compared for demographic features, stone characteristics, operative data, success, and complications.

Results:

The mean stone volume was 308 ± 85 (54–800) and 336 ± 96 (60–720) mm³ in SWL and RIRS groups, respectively (P = 0.46). There were no significant differences in success rates (60% vs. 70%, SWL and RIRS), auxiliary treatment rates (16.4% vs. 14%), and complication rates (26% vs. 24.5%). The number of active procedural sessions and number of anesthesia sessions was higher in the RIRS group (P < 0.001 and P < 0.001, respectively), while the procedural time and anesthesia time were higher in the SWL group (P < 0.001 and P < 0.001, respectively). Stone size was found to be an independent success predictive factor for both the treatment modalities.

Conclusions:

Both SWL and RIRS have similar success, complication, and auxiliary treatment rates. RIRS was superior in terms of total procedure and anesthesia durations, while SWL was superior in terms of numbers of anesthesia sessions and active procedure sessions. As both have similar success rates, the more minimally invasive SWL should be chosen for pediatric upper urinary system stones of less than 2 cm size.

Retrograde intrarenal surgery: An expanding role in treatment of urolithiasis

During the past 3 decades, the surgical management of kidney stones has undergone many technological advances and one is the development of the flexible ureteroscopy. The development of this instrument as well as ancillary equipment such as baskets, graspers, and others, and improvements in lithotripsy with Holmium: YAG laser have led to expand its indications with diagnostic and therapeutic management of medical issues of the upper urinary tract such as urolithiasis and urothelial tumors. The objective of this review is to describe its indications and results in the different scenarios for the treatment of urinary stones.

Retrograde intrarenal surgery using ureteral access sheaths is a safe and effective treatment for renal stones in children weighing <20 kg

INTRODUCTION

Surgical treatment of pediatric kidney stones has changed dramatically in recent years because of the miniaturization of surgical instruments and the availability of intracorporeal lithotripters. The retrograde intrarenal surgery (RIRS) technique is nowadays considered an effective and safe procedure but studies in very young children are lacking and use of a ureteral access sheath (UAS) has also been debated.

OBJECTIVE

To assess safety and efficacy of RIRS using UAS in children weighing < 20 kg.

MATERIALS AND METHODS

Data from 13 children weighing <20 kg who underwent RIRS for renal stones were collected. A Double-J stent was positioned 14 days before surgery. Demographics, stone location, stone number and composition, stone-free status (SFS) and complications were evaluated. Descriptive statistics were applied to describe the cohort.

RESULTS

Thirteen patients, age 3.91 ± 1.8 years (mean ± SD), underwent 16 RIRS. Mean patient weight and stone burden were 14.88 ± 3.81 kg (range 10-20 kg) and 15.5 ± 3.8 mm (median 16 mm), respectively. A UAS was used in 15 out of 16 (93.8%) procedures. SFS was achieved in 81.3% of cases after the first procedure and 100% after auxiliary procedures. Postoperative urinary tract infections with fever (Clavien II) were observed in two (12.5%) patients. Hydrocalyx (Clavien IIIb) was noted in one (6.3%) patient. Patients with stones located in the lower polar calices (p = 0.024) and with mixed composition (p = 0.036) had a greater prevalence of complications than those with calculi of other compositions located in other sites. After a mean follow-up of 22.4 months no cases of ureteral strictures or vesicoureteral reflux were observed (Table).

DISCUSSION

The current findings support previous evidence showing safety and efficacy of RIRS with use of the UAS in pre-stented very young children. In our experience RIRS seems to be an effective and safe option with a stone-free rate of 81.3% and only 1 severe complication (Clavien-Dindo grade IIIb) and no long-term complications. This study is, to date, the first to examine the safety and efficacy of RIRS using UAS for the treatment of intrarenal stones in a selected cohort of pre-school patients weighing <20 kg.

CONCLUSIONS

RIRS using UAS is an effective and safe procedure for treating kidney stones in pre-school patients weighing <20 kg without complications at both short and long term follow up. Stones of mixed composition located in the lower polar calices are associated with a greater risk of postoperative complications.

Clinical efficacy of percutaneous nephrolithotomy versus retrograde intrarenal surgery for pediatric kidney urolithiasis: A PRISMA-compliant article

BACKGROUND

Percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS) are widely used for pediatric upper tract stones; however, comparisons of their clinical efficacies are needed.

METHODS

Literature searches for relevant articles were performed using PubMed, the Cochrane Central Register of Controlled Trials, Embase and the China CNKI database. Study quality was assessed by Jadad and Newcastle-Ottawa Scales. Standard mean differences (SMDs) or odds ratios (OR), and 95% confidential intervals (95% CIs) were pooled for meta-analysis. In addition, data was evaluated the quality of the body of evidence by means of grading of recommendations assessment, development, and evaluation (GRADE).

RESULTS

Data from 4 studies (231 PCNL, 212 RIRS cases) were analyzed. There was no significant difference in operation time (SMD: 1.39; 95% CIs: -0.049 to 2.82; P = .058), overall stone-free rate (OR: 3.72; 95% CIs: 0.55-25.22; P = .18), or complication rate (OR: 1.92; 95% CIs: 0.90-4.07; P = .091). PCNL cases had longer hospital stays (SMD: 1.22; 95% CIs: 0.95-1.50; P < .001), but showed a higher stone-free rate for stones greater than 20 mm (OR: 6.38; 95% CIs: 1.83-22.22; P = .004). For stones less than 20 mm, however, no significant difference between PCNL and RIRS was found (OR: 0.92; 95% CIs: 0.33-2.55; P = .87). The quality of evidence based on the GRADE system was low.

CONCLUSION

Results of our systematic review and meta-analysis suggest that, for the treatment of larger kidney stones (>20 mm) in pediatric patients, PCNL is a better option due to its higher stone-free rate, although RIRS may be associated with shorter hospital stays. A large-scale clinical trial is necessary to validate our findings.

Retrograde intrarenal surgery in the management of pediatric cystine stones

OBJECTIVE

To investigate the efficacy and safety of retrograde intrarenal surgery (RIRS) in the treatment of pediatric cystine stones.

STUDY DESIGN

Data of the pediatric patients who underwent RIRS for kidney stones were retrospectively evaluated. A total of 14 children with cystine stones managed with RIRS were identified. In addition to the patient demographics and stone characteristics, all retrospectively obtained operative data were evaluated and discussed in detail, with an emphasis on the success and complication rates.

RESULTS

Mean age of the 14 cases was 10.9 ± 2.2 years (range: 7-15). Mean stone size was 13.6 ± 2.4 mm (range: 10-18) (Summary table). Of these stones, four were located in the renal pelvis, three were in the lower, three were in the middle and the remaining four were located in upper calyx. Ureteral access sheath was used in 12 (85.7%) patients. The double-J ureteral stent was placed pre-operatively in one case and was inserted postoperatively in 12 cases. Mean operation time was 38.2 ± 7.2 min (range: 30-50). Complications were observed in two cases: mild ureteral laceration in the first and fever on the second postoperative day in the second patient. All of the patients were stone free on sonographic evaluation at the 4-week follow-up evaluation. Although potassium citrate treatment was initiated in 11 patients, tiopronin treatment was initiated in four patients for recurrence prophylaxis during long-term follow-up. During a mean follow-up period of 25.7 ± 5.2 months, stone recurrence was noted in one patient.

DISCUSSION

Treatment of patients with cystine stones is challenging, due to high risk of rapid recurrence in the presence of residual fragments. Besides allowing complete stone clearance in all cases in the current series, RIRS is a highly reproducible method that can be safely performed, even in recurrences. The major limitations of the current study were low number of patients and short follow-up period.

CONCLUSION

The results clearly indicated that RIRS is a safe treatment modality in the management of pediatric cystine stones.

Extracorporeal Shockwave Lithotripsy Versus Flexible Ureteroscopy for the Management of Upper Tract Urinary Stones in Children

OBJECTIVE

To compare the efficacy and morbidity of extracorporeal shockwave lithotripsy (SWL) and flexible ureteroscopy (F-URS) for the management of upper tract urinary stones in children.

METHODS

All SWL and F-URS performed in children in a single institution between 2000 and 2014 were reviewed retrospectively. Only procedures performed to treat upper tract urinary stones (upper ureter or kidney) were included in this study. Preoperative and perioperative outcomes were compared between the SWL and F-URS groups. Univariate and multivariate logistic regression analyses were used to evaluate predictors of stone-free (SF) status.

RESULTS

Over the study period, 100 SWL and 46 F-URS were conducted in 69 children. The SWL and F-URS groups were comparable in terms of stone size (14.6 vs 13.2 mm, p = 0.32), but there were more multiple stones (31% vs 57%; p = 0.003) and lower pole calculi (14% vs 37%; p = 0.003) in the F-URS group. The SF rate after one procedure was almost two times higher in the F-URS group compared with the SWL group (37% vs 21%; p = 0.04) without increasing the complication rate (21.7% vs 16%; p = 0.31). Similar results were observed in the subgroup of single renal stones <20 mm (SF rates: 78.6% vs 50%; p = 0.06). In multivariate analysis, the use of F-URS vs SWL was a predictor of an SF status (odds ratio = 3.7; p = 0.02).

CONCLUSION

F-URS provides a higher single-session SF rate, despite more complex urinary stones (multiple, lower pole, etc.) and without increasing morbidity.

[Impact of the acquisition of a flexible ureteroscope on the management of upper urinary tract stones in children]

INTRODUCTION

Firstly reported in the early 1990s for the treatment of upper urinary tract stones in adult patients, flexible ureteroscopy (F-URS) has been used in children during the past 10 years and is now considered as a viable, but still second-line alternative to extracorporeal shockwave lithotripsy in these patients (ESWL). The aim of this study was to assess the impact of the acquisition of a F-URS on the management of upper urinary tract stones in children.

PATIENTS AND METHODS

Data of all ESWL, F-URS and percutaneous nephrolithotomy performed for upper urinary tract stones in children from 0 to 18 years old in a single center from 2000 to 2014 have been collected retrospectively. Patients have been divided into two groups: group 1 before the acquisition of the F-URS (2000-2008) and group 2 after the acquisition of the F-URS (2008-2014). Preoperative data and peri-operative outcomes were compared between both groups using the χ(2) test and Fisher exact test for discrete variables and the Mann-Whitney test for continuous variables.

RESULTS

Thirty-seven children have been treated during the first era and 32 during the second one. The two groups were similar in terms of age (7.2 years vs 8.1 years; P=0.54), size of the largest stone (15 mm vs 16.2mm; P=0,56) and number of stones per patient (1.4 vs 2; P=0,07) but the sum of stone diameters was higher in group 2 (16.9 mm vs 24.2mm; P=0,048). The stone-free rates were comparable in both groups (28.1% vs 32.2% after the first procedure; P=0.72), as were the mean number of procedures per patient (2.4 vs 2.5; P=0.78), the total length of stay (2.7 days vs 2.9 days; P=0.77), and the number of patients who experienced at least one complication (37.8% vs 40.6%; P=0.87).

CONCLUSION

The acquisition of a F-URS allowed the treatment of more complex stones with a similar efficacy and without increasing morbidity. Further studies are needed to define the role of F-URS in the management of upper urinary tract stones in children.

How should patients with cystine stone disease be evaluated and treated in the twenty-first century?

Cystinuria continues to be one of the most challenging stone diseases. During the latest decades our knowledge of the molecular basis of cystinuria has expanded. Today 160 different mutations in the SLC3A1 gene and 116 in the SLC7A9 gene are listed. The full implications of type A, B or AB status are not yet fully understood but may have implications for prognosis, management and treatment. Despite better understanding of the molecular basis of cystinuria the principles of recurrence prevention have remained essentially the same through decades. No curative treatment of cystinuria exists, and patients will have a life long risk of stone formation, repeated surgery, impaired renal function and quality of life. Therapy to reduce stone formation is directed towards lowering urine cystine concentration and increasing cystine solubility. Different molecules that could play a role in promoting nucleation and have a modulating effect on cystine solubility may represent new targets for cystinuria research. Investigation of newer thiol-containing drugs with fewer adverse effects is also warranted. Determining cystine capacity may be an effective tool to monitor the individual patient's response. Compliance in cystinuric patients concerning both dietary and pharmacological intervention is poor. Frequent clinical follow-up visits in dedicated centres seem to improve compliance. Cystinuric patients should be managed in dedicated centres offering the complete range of minimal invasive treatment modalities, enabling a personalized treatment approach in order to reduce risk and morbidity of multiple procedures.